/**
 * Project: complex.mina
 * 
 * File Created at 2011-8-17
 * $Id$
 * 
 * Copyright 2008 Alibaba.com Croporation Limited.
 * All rights reserved.
 *
 * This software is the confidential and proprietary information of
 * Alibaba Company. ("Confidential Information").  You shall not
 * disclose such Confidential Information and shall use it only in
 * accordance with the terms of the license agreement you entered into
 * with Alibaba.com.
 */
package com.complex.nio;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.nio.charset.Charset;
import java.util.Iterator;
/**
 * TODO Comment of NIOServer
 * 
 * @author ymkyve
 */
public class NIOServer {
    // 本地字符集
    private static final String LocalCharsetName = "gb2312";

    // 本地服务器监听的端口
    private static final int    Listenning_Port  = 8888;

    // 缓冲区大小
    private static final int    Buffer_Size      = 1024;

    // 超时时间,单位毫秒
    private static final int    TimeOut          = 3000;

    public static void main(String[] args) throws Exception {
        // 创建一个在本地端口进行监听的服务Socket信道.并设置为非阻塞方式
        ServerSocketChannel serverChannel = ServerSocketChannel.open();
        serverChannel.socket().bind(new InetSocketAddress(Listenning_Port));
        serverChannel.configureBlocking(false);

        // 创建一个选择器并将serverChannel注册到它上面
        Selector selector = Selector.open();
        serverChannel.register(selector, SelectionKey.OP_ACCEPT);

        while (true) {
            // 等待某个信道就绪
            if (selector.select(TimeOut) == 0) {
                System.out.println(".");
                continue;
            }

            // 获得就绪信道的键迭代器
            Iterator<SelectionKey> keyIter = selector.selectedKeys().iterator();

            // 使用迭代器进行遍历就绪信道
            while (keyIter.hasNext()) {
                SelectionKey key = keyIter.next();

                // 这种情况是有客户端连接过来,准备一个clientChannel与之通信
                if (key.isAcceptable()) {
                    SocketChannel clientChannel = ((ServerSocketChannel) key.channel()).accept();
                    clientChannel.configureBlocking(false);
                    clientChannel.register(key.selector(), SelectionKey.OP_READ,
                            ByteBuffer.allocate(Buffer_Size));
                }

                // 客户端有写入时
                if (key.isReadable()) {
                    // 获得与客户端通信的信道
                    SocketChannel clientChannel = (SocketChannel) key.channel();

                    // 得到并重置缓冲区的主要索引值
                    ByteBuffer buffer = (ByteBuffer) key.attachment();
                    buffer.clear();

                    // 读取信息获得读取的字节数
                    long bytesRead = clientChannel.read(buffer);

                    if (bytesRead == -1) {
                        // 没有读取到内容的情况
                        clientChannel.close();
                    } else {
                        // 将缓冲区准备为数据传出状态
                        buffer.flip();

                        // 将获得字节字符串(使用Charset进行解码)   
                        String receivedString = Charset.forName(LocalCharsetName).newDecoder()
                                .decode(buffer).toString();

                        // 控制台打印出来
                        System.out.println("接收到信息:" + receivedString);

                        // 准备发送的文本
                        String sendString = "你好,客户端. 已经收到你的信息" + receivedString;

                        // 将要发送的字符串编码(使用Charset进行编码)后再进行包装
                        buffer = ByteBuffer.wrap(sendString.getBytes(LocalCharsetName));

                        // 发送回去
                        clientChannel.write(buffer);

                        // 设置为下一次读取或是写入做准备
                        key.interestOps(SelectionKey.OP_READ | SelectionKey.OP_WRITE);
                    }
                }

                keyIter.remove();
            }
        }

    }
}
